Telephony.



H. D. GURRIER.

TELEPHONY. H APPLICATION FILED JULY 20,1908.

Patented Dec. 22, 1908.

.525 aliases the ,teleplhone line 0, (though it- Application filed call conccm: v, knewn-;;that l,1;H mam D. CURRIE-R, citizen of the United States, residing at Chie- -cago, ,in the county-of Cookand State of Illi- 5 nols hayejnyented acjertain new anduseful royegnent 131 1 61611 1611),- ofwhich the i ull,fclear,concise, andexact 'description,reference.jbeing'had to the acv oompanyingdrawingsyforming a part of this 9 P 9!fi 21Q i y erenti to telephon I audits J Q 'F fi ldkd fi tages will be we undert d by wmffitence to the; accompan i drawing, v a Figure 1 ;shows fone embodiment Fig. -another embodiment thereof; ,eferrinsggfirstto the. embodiment of the invention; QWn.;- H l 7 11:, I have illustrated ciroliit; a w ioh is shown as con {telephonestation 1 (which, for etcamfiletmay beIa train despatcheris office) I 'wit pfqur or: other: number of telephone stations, 1.;2,- 3, '4 15; Each telephone station. inclqdes a oridge conductor 1) unitingthe meunderstood t at .I do not limitmy hwention' jt o metallic-telephone circuit within whiohlbridge conductor there in-1 eluded-at, chastation a telephone switchhook ameoeiverd and'thesecondaiyfof an;

induction bridgecon'ductorb at ,the stations.2;i3, 4fandr5also includes a. retardation :cbils c that serves to determine theefiective res'istanoe offered to thetalking v 5 currentimpressed upon said bridge conduc-- qtor at'ithe hner i The primary g of the induction coil, at eaeh telephone station is shown included in a local circuit with a transmitter kand a-Ebattery i, which may, if desired, be of' 40 eleven volts pressure. Thereis also shown flatreachstationv a shunt conductor k, which includes Ha retardation coilfl of low ohmic resistance. {Thec'onductor' -7 and "the local" circuit afonthe: transmitter. 71) include each a 45, ;pairx-of-contacts "m and n, respectively,'the. contacts of! each of the sets and n' being normi lly in separated relation. "The con tactsrof bothsets are simultaneously engaged n? the operation-ofa-ke 0-, the operation ifvhich key is to occur' W en the receiver-d, of the-associate station is removed from its; switch-hook c "fwhell the party at sucha station-is togtalk When partyat such station glad-listen,- the "button as, If the train-despaicher orotheripart at thegsta tmnreceiver.

a erect-m i I specificationof Letters Patent."

ation'of the transmitter h.

incidentally o-is released. f

i 3 iemade less than the eflective resistance of :tbeJ-bridge-condnctor at the train'line station ES ATENT OFFICE. fHi A D GU R E t Q EQiI EOAQ I rLLiNroisj v v 1 I ram ed net. 22, 1908.

shunted "by the conductor upon the operatlOH'Of the button'o, the associate transmitter circuit g h'i beingat the same time closed. By the closure of the contacts m at station 1, a, conductance path of com aratively low .efl ectiveresistance is establis ed about the telephone'receiver'd. By this feature of my invention I 'am ena'ble'dto eliminate a large portion of the efiective resistance to the outa going volce currents that are impressed upon the secondary f as aconsequence of the oper- 1 The conductor .k at ea'oh'ofthe stations 2, 3 4'and 5 not only I establishes ashunt about the telephone rethereof,

ceiver d at each of said stations when said conductor is is closed at m at each station,

"but'said conductor k at each station is also 50 connected as to shunt the retardation coil 0 'thereatlaswell. iBy shunting the receiyer dan'd retardation-coils, when talking, the effective, resistance offered to the flow ofimpressed voice currents from the secondary f to thelineis' not only reduced,*but side tones atthe receivers 65 are eliminated, which is also'the case with the receiver at station 1 when the shunt conductor is thereat is closed at m. It is to 'be'understood that the key 0 at astation-is operated only when voicecurrents'are to beimplessed upon the line at suchstation and that such key 0 is to be .released'when voice currents are to bereceived at suchs't'ation, the. strength of the batteries being, saved by opening the trans'r'nittercircuits during the time the receivers have the shunts removed therefrom. Much difiicult has been, experienced in the past in equall y distributing the voice currents to a plurality of telephone stations which were connected simultaneously to a telephone line when the despatcher desired to convey the same information to a number of stations, as is the case in putting out a train order. I overcome this difficulty by suiting the effective resistance of each bridge conductor b to itsdi's'tancefrom the des patchers office or other station, 1. Thus, where retardation coils c are employed, the

efleoti've' resistance of the bridge conductor at station 2 is caused to be greater by the re-' 'tardation coil 0 than the effectiveiresistance.

of the bridge conductors I) at the other train :linestation's that .more remote from the des tchers ofiice .1; ofthg'bndge conductor 72. at trainline station the efiective resistance 2, but greater than the effective resistances of the bridge conductorsat stations 4 and "-5, that are more remote from the de spatchers office 1 than stations 2 and 3; the effective resistance of the bridge conductor at station 4 is less than the effective resistance of the bridge conductors at stations 2 and 3 and greater than the effective resistance of the bridge conductor 12 at station 5. The effective resistances offered by the bridge 'con-,

ductors b at stations 2, 3, 4 and are desir- 'ably made adjustable, and such adjustment may be accomplishedwhere retardation coils are employed by having the cores for said coils slidable Within the bores of said coils. By thus varying the effective resistances of the bridge conductors at the different train line stations, the effectiveness of the voice currents received at each of such stations may be made approximately equal. This is due to the fact that the impedance, or effective resistance of the different "bridges is including the receiver.

-one of the stations;

tapered in value from the despatchers end of the line to the other end thereof. For ex ample, it is possible with this arrangement to so adjust the effective resistance of the conductor b at station 2, that it is equal to the effective resistance of the corresponding eonductor of the station at the other end of the line plus the line resistance. The retardation coil Z; included in each shunt conductor 7c has an adjustable core to vary the effect of the shunt upon the circuit The purpose of this adjustable impedance which is normally low in value, is to permit voice currents to pass through the receiver, rovided the despatcher desires to interruptt e erson talking at any have this impedance low so as not to dissociate outgoing voice currents from the stations, it is found preferable to make it adjustable so that the break in "feature described above may be obtained'. In. practice, it is found only necessary that the person talking should receive enough current to knowthat the despateher is on the line, in which event the party talking releases the key 0 and receives the full talking current from the line.

The effective resistance offered by the small retardation coil Z at each train-line station that is nearer the transmitting station, is caused to be greater than that offered b each more distant impedance coil Z. The a justment of the effective resistances at each of the train line stations 2,3, 4 and 5 may also'b'e accomplished, as shown in Fig. 2, by

. substituting condensers p for the retardation coils at such-stations, the capacity of the office.

condensers increasing with the distance of the train line stations from the despatchers In other respects the system shown in Fig. 2 is similar to the system shown in Fig. 1. In neither of these systems have I deemed it necessary to illustrate the signalt being desirable to claim as new and desire to secure by Letters Patent the following:'

1. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon the km, a plurality of receiving stations having telehone receivers included in conductors in ridge of the tele hone line, and which conductors offer difiering degrees of effective resistance to the voice currents impressed thereupon by the transmitting station, each bridge conductor that is nearer the transmitting station having more effective resistance than each more distant bridge condnctor.

2. A telephone systemincluding a tele phone line, a transmitting station at which voice currents are impressed upon the line, a plurality of receivin stations havingtelehone receivers inclu ed in conductors in ridge of the telephone line, and which conductors offer difiering degrees of adjustable" eflective resistance to the voice currents im-' pressed thereupon by the transmitting station, each bridge conductor that is nearer the transmitting station having more effective resistance than each more distant bridge con-. ductor.

3. A telephone system including a telephone line, a transmitting station at which I voice currents are impressed upon the line a plurality of receiving stations having. telehone receivers included in conductors in ridge of the telephone line, and which conductors offer differing degrees'of impedance to thevoice currents impressed thereupon by the transmitting station, each bridge conductor that is nearer the transmitting station having more im edance than each more distant bridge con uetor.

4. A telephone system including a telephone line,a transmitting station at which voice currents are impressed upon the'line, a plurality'of receiving stations having telephone receivers included in conductors in ridge of the. telephone line, and which conduetors offer differing degrees of adjustable imped'anceto the voice currents im ressed thereupon by the transmitting station, each bridge conductor that is nearer the transmittin station having more impedance than eacli 'more distant bridgeconductor,

5. A telephone system including. a telephone line, a transmitting station at which voice currents are impressed upon the line,'a plurality of receiving stations having tele- Ei-idge ridge of the telephone line, the effective resistance of said conductors beingadjustable. 6. A telephone system including a tele-,

phone line, a transmitting station at which voice currents are impressed upon the line, a plurality of receiving stations having telehone receivers included inconductors in of the telephone line, and adjustable impedance included in said conductors. V 7. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon the line, .a plurality of receiving stations having telephone receivers included in ,conductors in ridge of the telephone line, and which conductors ofi'er difiering degrees of eiiective resistance '-to the; voice currents impressed thereupon by the transmitting station, the differing degrees of effective resistance when added to the line resistance between any par tioular station and the transmitting station,

,tions to the transmitting station.

being approximately the same from all sta- 8. A telephone system including a telephone line, a transmittin ipon the line, a on having telephone receivers included in conductors in bridge of the telephone line, and which conductors otter differing degrees of impedance to the voice currents impressed thereupon by the transmitting station, the differing degrees of impedance when added to the line resistance between any particular station and the transmitting station afiording approximately the same effective resistance rom all stations to the transmitting station, In Witness whereof, Lhereunto subscribe my namethis 18th day of July A. 1)., 1908.

HIRAM D. CURE-IE3.

Witnesses:

L. G. STRon, G. L. CROGG.

I ation at which vo1ce currents are impress..- plurality of receiving statr 

